Analysis Of URO Gene Tobacco Transformants And Function Of URO DOWNSTREAM 1 Gene

The transcription factor URO can regulate endogenous auxin homeostasis in plants, which belongs to C2H2 plant-specific gene family. Our previous studies showed that overexpression of URO genes in Arabidopsis leads to a significantly increase of free IAA, and then a series of auxin-related phenotypes appeared. Such as the reduction of apical dominance and plant height and an increase of the number of lateral branches, etc.In order to fully study the function of URO gene and its conservativity, we transfered Arabidopsis URO gene into tobacco by Agrobacterium tumefaciens mediating, which makes tobacco phenotype significant changes, including the reduction of apical dominance and plant height, thicker and more curled leaves, flower abnormalities, decreased fertility, etc. These phenotypes have many similarities to uro mutant in Arabidopsis.On the basis of preliminary analysed of URO tobacco transformants, we Continued to transformate, expanded the populations of transgenic tobacco. Further observations and studies of the phenotypes, physiological characteristics and genes expression of URO tobacco transformants have been done. Our study showed that URO tobacco transformants flowering and senescence were delayed. Further studies showed that transgenic plants’ chlorophyll content and photosynthetic efficiency have increased. In addition, we found that the volume of leaf cells has significantly increased. By flow cytometry, the results showed that the Polyploid cells of URO transformant have increased. The construction of pGH3-GUS can reflect plants’ auxin signal.We transfered it into URO gene transformants, the results showed that the signal of IAA in transformants was stronger than the empty vector control. We cultured the detached leaves of URO gene transformants on hormone-free medium, which can produce adventitious roots. These results proved that overexpression URO gene in tobacco can increase auxin concentration of the transformants.The results above suggest that the function of URO gene in higher plants was conserved and it can be used for research and renovation work of auxin content. In addition, the phenotypes of URO gene transformants suggested that the function of URO gene may take part in endoreduplication and the regulation of cell division. Overexpression of URO gene can maintain a high state photosynthetic efficiency of leaves, which have some application prospect.On the basis of preliminary work, the researchs of URO DOWNSTREAM 1(UD1) gene which may be the URO gene’s downstream gene have been done. According to add reporter gene to UD1’s promoter and in situ hybridization, we identified temporal and spatial expression of UD1 gene which has some Similarity to URO gene. Meanwhile we analyze the UD1 gene overexpressed transformants and loss of function mutant. These results demonstrated that UD1 which belong to GH3 gene famliy is the downstream gene of URO gene.